Thursday, June 25, 2015

Hot hand fallacy disproved

Statisticians frequently point to the Hot-hand fallacy, and argue that random events are uncorrelated. That is normally true for events like coin tosses and roulette wheels, but is often applied also in sports where a correlation would be expected.

Most sports fans and athletes believe in hot streaks. A basketball player who has hit several shots in a row, the thinking goes, has a greater chance of hitting the next one, due to a "hot hand." Think of Golden State Warriors guard Stephen Curry, who recently hit 77 straight three-pointers in practice.

Yet for a long time, scientists were skeptical. In 1985, a hugely influential study by a trio of psychologists argued that the hot hand was a myth. Among the NBA and college players they studied, hitting one shot made no difference in their odds of hitting the next shot. Like coin tosses, players were subject to the laws of probability, with the same baseline percentage chance of hitting every shot. Ever since that study, psychologists have held up fans' belief in the hot hand as an example of human irrationality: our tendency to see patterns in randomness.

Now, however, it's starting to look like the hot hand might be real after all.

"Psychologists thought it was just our tendency to see patterns in randomness"

A handful of studies published over the past few years have suggested that basketball players, pro bowlers, and volleyball players can indeed heat up, boosting their normal accuracy rates by several percentage points for longer stretches of play than you'd expect from chance.

And last week, a new study found one of the strongest pieces of evidence for the hot hand yet. The researchers looked at 29 years' worth of data from the NBA three-point shooting contest and found that players who hit three or more shots in a row had a 6.3 percent higher chance of hitting the next one, compared with their baseline rate.

This hot hand fallacy is frequently given as proof of a cognitive bias.